Where is bay pollution coming from? Scientists turn to the currents

– September 13, 2016

Trash piling up on shores around Miami prompted local museums to ask University of Miami scientists working on the BP oil spill to apply their research to pollution swirling around Biscayne Bay. Photo Credit: Vizcaya Museum & Garden.

In mangroves behind Vizcaya, plastic bottles, tampon applicators and bits of styrofoam regularly get trapped in the tangle of roots as if captured in a storm drain. Out the mouth of the Miami River and across Biscayne Bay on Miami Beach, stormwater flushes human and animal wastes and an array of foul stuff. On Virginia Key, a vial of blood sticks out of the sand.

How trash gets there and where that and other pollution flows around Biscayne Bay remain largely a mystery. But now a team of University of Miami scientists think they may know how to find the answer.

Using technology developed to track the Deepwater Horizon oil spill in the Gulf of Mexico, the researchers have teamed up with school kids and local museums to track the complex network of micro currents that crisscross the bay, spreading trash and pollution. While they concede the project is just a beginning, they hope mapping the currents will help inform government planners as they tackle a host of increasing threats to the urban but still vital bay — from flooding tied to rising seas to bigger ships sailing through the Panama Canal.

“We actually know very little because the geometry is so complicated,” said Rosenstiel School of Marine and Atmospheric Science oceanographer Tamay Özgökmen, who leads a consortium of 40 scientists from 14 universities studying the BP spill.

“Does it flush to the ocean or does it just stay where people live for a long time and then you have to worry about bacteria and all kinds of health issues?” he said. “Not flushing is not good.”

On Monday, Özgökmen’s team released 15 sensors specifically designed to measure currents at the surface of the water, where wind and waves can whip around much faster than deeper currents. The sensors — floating white rings attached to an underwater foot-wide pinwheel — include a small GPS tracker that lets the team calculate the speed and path of currents. While the technology seems simple, it took three scientists two years to come up with a device that was light, compact, biodegradable (the plastic was developed by MIT scientists for beach toys) and capable of separating the forces of waves, wind and ocean currents.